A desilylative approach to alkyl substituted C(1)-ammonium enolates: application in enantioselective [2+2] cycloadditions

Yihong Wang, Claire Mary Young, Honglei Liu, Will Hartley, Max Wienhold, David Bradford Cordes, Alexandra Martha Zoya Slawin, Andrew David Smith*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)
5 Downloads (Pure)

Abstract

The catalytic generation of C(1)-ammonium enolates from the corresponding α-silyl-α-alkyl substituted carboxylic acids using the isothiourea HyperBTM is reported. This desilylative approach grants access to α-unsubstituted and α-alkyl substituted C(1)-ammonium enolates, which are typically difficult to access through traditional methods reliant upon deprotonation. The scope and limitations of this process is established in enantioselective [2+2]-cycloaddition processes with perfluoroalkylketones (31 examples, up to 96% yield and >99:1 er), as well as selective [2+2]-cycloaddition with trifluoromethyl enones (4 examples, up to 75% yield and >99:1 er). Preliminary mechanistic studies indicate this process proceeds through an initial kinetic resolution of an in situ prepared (±)-α-silyl-α-alkyl substituted anhydride, while the reaction process exhibits overall pseudo zero-order kinetics.
Original languageEnglish
Article numbere202208800
Number of pages9
JournalAngewandte Chemie International Edition
Volume61
Issue number38
Early online date8 Aug 2022
DOIs
Publication statusPublished - 12 Sept 2022

Keywords

  • B-lactone
  • Cycloaddition
  • Desilyation
  • Enolate
  • Isothiourea

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